A bolt was fired through a window of an elderly woman's Whangamata home this morning and police believe it may have been shot from a device using gunpowder from fireworks.

Police Senior Sergeant Rupert Friend said the woman, who lived on Weka St, was woken up by a loud bank about 1am.

"At first she thought it might have been a rock thrown through her window, which was frightening enough, but when neighbours came to check she was alright after hearing a live bang, they discovered her curtain ripped; things appeared a bit more serious,” he said.

"Neighbours rang police about a broken window at the time, but then at first light this morning she noticed a half inch bolt lying on her lounge room floor and we were called again things started to frame a different picture."

Friend said the bolt smelled of gunpowder and police found cardboard tubing from fireworks that had been unrolled on the road outside.

Police were appealing for anyone in the vicinity of Weka St, Whangamata, about 1am and who may have noticed anything suspicious, to contact them.